Phonographic apparatus



Sept. 9, 1941. J. J. HOEHN PHONOGRAPHIC APPARATUS Filed Nqv.. 50, 19:592 Sheets-sheaf, 2

Zmnentor Patented Sept. 9, 1941 rnoNoGn'Armc APPARATUS John J. Hoehn,Indianapolis,-Ind., assignor to Radio Corporation of America, acorporation of Delaware Application November so, 1939, Serial No.306,833 7 Claims. (01. 274-9 This invention relates to phonographicapparatus, and more particularlyto recording apparatus used inrecordingupon blank discs or cylinders which may be played back immediately afterrecording, the present invention being in the nature of an improvementupon that disclosed in the copending application of Harold J.

Hasbrouck, Jr., Serial No. 256,270, filed February 14, 1939, andassigned to Radio Corporation of America.

In the said copending application, there is disclosed a recordingmachine wherein the recording head is carried on a pivotally mountedcradle and is fed across the record by a feed screw which may be drivenfrom the turntable spindle, for example, damping means being provided inconjunction with the aforesaid cradle to prevent substantial vibrationor oscillation of the cutter head in a direction normal to the surfaceof the record with which the cutting stylus is in contact. -Anadjustable spring'is provided for regulating the depth of cut of thecutting stylus.

While a construction of this sort afiords very good results, the load ofthe cutter head on the supporting bearing therefor is relatively greatand the cutter head does not oscillate as freely on. its bearings as issometimes desirable, par- In accordance with my present invention, 1.

suspend the floating cutter head mounting bracket or cradle by means oftwo separated tension springs. The tension of one spring is preferablymade adjustable-by means of a suitable screw and thumb nut to controlthe depth of the cut groove, while the assisting spring is preferably offixed tension, although it may also be made adjustable as to tension ifdesired. In any case,.the tension of the assisting spring is weaker thanthat of the'spring which controls the cutting depth. It follows,therefore, that the two springs cannot have the sameperiods, andtherefore the control of the vertical oscillation of the cutter and itscarriage passes automatically from one spring to the other. At

the same time, theme of two springs, one on .each side of the cutterhead, balances the load on the cuter head mounting bearings.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation, aswell as additional objects and advantages thereof, will best beunderstood from thefollowing description of one embodiment thereof, whenread in connection with the 1 accompanying drawings in which ticularlysince there is an unequal load on the two pivot bearings, so that bestresults can not always be obtained with a construction of this sort. Y

The primary object of my present invention is to provide an improvedcutter head suspension for recording machines wherein the aforementioneddifllculty is obviated.

More particularly. it is an object of my present invention to provide,in phonographic apparatus as aforesaid, an improved cutter headsuspension wherein the load on the cutter head mounting bearings will bebalanced, or substantially equalized, thereby providing freedom foroscillatory movement of the cutter head.

Another object of my invention is to provide an improved cutter headsuspension by means of which more delicate adjustment of the depth ofthe needle cut will be possible.

A further object of my present invention is to provide an improvedcutter head suspension, as above described, which can be readily adaptedto existing recording machines.

It is also an object of my present invention to provide an improvedcutter head suspension, as aforesaid, which is very simple inconstruction and highly efilcient in use.

- carrying a pair of guide rods 5 and a rotatable Figure 1 is a frontelevation of a portion of a recording machine showing my improved cutterhead suspension applied thereto,

Figure 2 is an end elevation as seen from the left in Fig. 1,

Figure'3 is a sectional view taken on the line III-111; of Fig. 1, and

Figure 4 is a sectional view taken on the. line IVi-IV of Fig. 1.

Referring. more particularly to the drawings, wherein similar referencecharacters designate corresponding parts throughout, there is shown amotor board i upon which is pivotally mounted for universal movementthereon a frame 3 feed screw 1 on which a carriage 9 is slidably androtatably mounted, the carriage 9 being provided with a pair ofdownwardly and forwardly extending arms H. The carriage 9 also pivotallycarries a latch lever. II which is formed with a half nut l6 adapted tocooperate with the feed screw 1 whereby the carriage 8 and theparts'carried thereby may be fed radially across a record blank Rsupported an a suitable turntable ii. The latch lever I3 is alsoprovided with a latching toe i8 which is adapted to engage the upperguide rod 5 when the carriage Sand the latch lever l3 are rotated on thefeed screw 1 a suiilcient distance in a counter-clockwise direction, asviewed in Fig. 2.

Arranged to cooperate with the record blank R is the cutting stylus 2.1of a cutter head 23 to which is fixed a rearwardly extending cradle 25pivotally mounted on a pair of spaced pivot bearings 21. The pivotbearings 21 extend in opposite directions, as clearly shown in Fig. 1,and are carried by a pair of parallel links 29 which, in turn, arepivotally mounted on a pair of spaced, cooperating pivot bearings 3|carried by the arms ll of the carriage 9, the ,carriage 9 thusconstituting a supporting member for the cutter head 23, its cradle 25,the bearings 21-, the links 29 and the-bearings 3|. A damping member 32of any suitable construction is preferably provided for the cutter head23 by securing it to the cradle 25, for example.

Slidably mounted within the carriage-9 for vertical movement thereon isa suitable block 24 which may be adjusted in a vertical direction bymeans of a thumb screw 33, a link 35 connecting the aforesaid block withthe links 29 to permit adjustment of the assembly in a direction normalto the surface of the record R. In addition, there is pivotally mountedon the aforesaid block an operating handle 31 which pivotally carries aconnecting link 39. The linkv 39 has a slot 4| formed on its lower endto receive a pin 43 on the cradle 25. To raise the cutting stylus 2|from record blank R, it is merely necessary to raise the handle 31whereupon the play in the slot 4| is first taken up, after which the endof the slot engages the pin 43 to raise the cradle 25 and the cutterheadl23. Lowering of the handle 31 will, of course, bring the cutterhead 23 back into engagement with the record blank R.

To balance the load of the cutter head 23 on ,the pivot bearings 21 and3|, I have provided a pair of tension springs 45 and 41. The spring 45has one end fixed to a pin 49 on the cradle 25 and its other end securedtoa screw which is adjustable by means of a thumb nut 53 on an extension55 of a bracket 55 fixed to the block 24. Adjustment of the thumb nut 53varies the tension in the spring 45 and thereby more or lesscounterbalances the cutter head 23 to regulate the depth of .cut of thecutting stylus 2|.

' weaker than is customary and therefore a finer adjustment of thecutting depth of stylus 2| is possible. Moreover, by making the tensionof the fixed spring 41 weaker than the tension of the spring 45, it isobvious that the two springs will not .have the same periods, and thecontrol or the vertical oscillations oi the cutter carriage will spring41.

automatically pass from the spring 45 to the Although I have shown anddescribed but one embodiment'of my invention, I am fully aware thatother modifications are possible, and I therefore desire that myinvention shall not be limited except insofar as is made necessary bythe prior art and by the spirit of the appended claims.

1. In phonographic apparatus, the combination of a supporting member, apivotal mounting thereon including spaced bearing parts, a soundtranslating device pivotally carried by said mounting, and meanscomprising a plurality of resilient members substantially equalizing theload of said pick-up on said bearing parts,

2. In phonographic apparatus, the combination of a supporting member, apivotal -mounting thereon including spaced bearing parts, a soundtranslating device pivotally carried by said mounting, and a pair ofsprings substantially equalizing the load of said pick-up 'on saidbearing parts.

The spring 41 is preferably of a fixed, predeter- 3. In phonog raphicapparatus, the combination of a supporting member, a pivotal mountingthereon including spaced bearing parts, a sound translating devicepivotally carried by said mounting, and a pair of tension springssubstantially equalizing the load of said pick-up on said bearing parts,said springs each having a different tension.

- 4. In phonographic apparatus, the combination of a supporting member,a pivotal mounting thereon including spaced bearing parts, a soundtranslating device pivotally carried by said mounting, a pair of tensionsprings substantially equalizing the load of'said device on said bearingparts; and means for adjusting the tension of at least one of saidsprings.

5. In phonographic apparatus, the combination of a supporting member, apivotal mounting thereon including spaced bearing parts, a soundtranslating device pivotally carried by said mounting, a pair of tensionsprings substantially equalizing the load of said device on said tion toeach other, a cradle pivotally carried by said bearings, a soundtranslating device carried by said cradle, and a pair of tension springsconnecting said cradle to said supporting member, one of said springsbeing located adjacent one of said bearings and the other of saidsprings being located adjacent another of said bearings,

the tensions of said springs being or such a magnitude as tosubstantially equalize the load on each of said bearings.

JOHN J. HOEHN.

